1. Field of the Invention
The present invention relates to a method for identifying nucleic acid sequences using two or more hybridization probes which hybridize to the same nucleic acid sequence.
2. Description of Related Art
A variety of assays have been developed to detect the presence of a particular nucleic acid sequence, hereinafter referred to as a target sequence, through selective hybridization of a hybridization probe to the target sequence. In order for a hybridization probe to hybridize to a target sequence, the hybridization probe must contain a nucleic acid sequence that is at least partially complementary to the target sequence. The complementary sequence of the probe must also be sufficiently long so that the hybridization probe selectively hybridizes to the target sequence over non-target sequences.
In addition to hybridizing a hybridization probe to a target sequence, the hybridization probe must be detectable. A variety of sandwich hybridization assays have been developed which identify a target nucleic acid sequence through the hybridization of a target nucleic acid sequence to two different hybridization probes. The first step of the assay generally involves the hybridization of a target nucleic acid sequence to a first hybridization probe. The hybridized pair is then generally immobilized to a solid support. A second hybridization probe containing a detectable marker is then hybridized to the target sequence, thereby enabling the target sequence hybridized to the first hybridization probe to be detected.
Sandwich hybridization assays require the use of two different hybridization probes where each hybridization probe hybridizes to a separate, non-overlapping portion of the target nucleic acid sequence. However, it is not always possible to design two hybridization probes to a target sequence where each hybridization probe hybridizes to different non-overlapping portions of the target sequence. As a result, some prior art sandwich hybridization assays employ hybridization probes that are not specific for the target nucleic acid. This significantly limits the quantitative accuracy of the assay for detecting target nucleic acid sequences in a sample.
It is an object of the present invention to provide an efficient hybridization assay for the identification of target nucleic acid sequences using two or more hybridization probes which hybridize to the same sequence of a target nucleic acid.